1. Field of the Invention
The present invention relates to a rolling bearing for supporting a rotary portion such as a hard disk drive (HDD) device for a computer or the like.
2. Related Background Art
Conventionally, to a rolling bearing used for a spindle device of a hard disk drive unit or the like, a caulked type or latched type shield plate has been attached.
When a conventional caulked type shield plate with no slit or cut-away portion is assembled to a rolling bearing by being caulked, there is a case where the shield plate is not held or supported with a stability because of deformation of a groove of an outer race member caused by thermal processing, or the like.
When the shield plate is caulked into the groove of the outer race, stress is apt to be concentrated onto a smaller diameter portion of the deformed portion at the groove of the outer race member deformed due to thermal processing. That deformation is apt to affect on an outer diameter portion of the outer race member, thereby causing deteriorated roundness or circularity.
Till now, no consideration has been paid to the number of the slit or cut-away portions even in the case where the shield plate formed with slits has been used.
The inventors have found that a rolling bearing with a shield plate formed with nZ or (nZ.+-.1) slit or cut-away portions (that is, the number of slit or cut-away portions of the shield plate is nZ or (nZ.+-.1), where n is a positive integer, and Z is the number of balls,) has a problem that vibration non-synchronous with rotation of the rolling bearing, that is, non-repetitive runout of the rolling bearing increases.
Such shield plate is attached, by being caulked, to a stepped portion of the groove formed on the outer race of the bearing. However, if the slit or cut-away portion(s) is (are) formed at the position of a curled bottom portion of the shield plate, the shield plate can not continue the tight contact relationship with the stepped portion of the groove of the outer race member, and this has caused a problem that grease in the bearing leaks out during the working time of the bearing.
Moreover, the conventional shield plate has another problem that, in the case where an angle is provided at the stepped portion of the groove of the outer race member, grease would leak out in the similar manner as last discussed herein above.